Why Can’t We Build Houses with Sand from the Beach?

Constructing a house using materials easily found in nature is the perfect choice to minimize cost and impact on the environment. Sand, particularly from beaches, is much available and thought of as a natural resource for building. But much as it is found in abundance, beach sand is not found suitable for house and other structure constructions. This article explores the scientific, economic, and environmental justifications for which beach sand is not suitable for construction purposes and what other options there are.

1. The Composition and Shape of Beach Sand

1.1. Grain Shape and Size

One of the primary reasons why beach sand is not suitable for construction is due to the shape of its grains. Beach sand grains are rounded due to ongoing erosion by wind and water. The tides and waves polish the sand grains over time, and they become smooth and spherical in shape.

In comparison to construction sand (which is often crushed stone or river sand), it possesses rough and angular grains which are sharp-edged. Such angular grains pack closely together, producing an even stronger bonding when mixed with cement in concrete or mortar. Beach sand rounded grains refuse to bind, making the concrete thereby produced weak and subject to crumbling.

1.2. Variability in Particle Size

Construction sand has to have a particular grain size range in order to pack well and give strength. Beach sand, on the other hand, tends to be mixed with fine and coarse grains, which do not pack well with cement. The random particle distribution creates weak points in concrete that lead to it failing structurally over time.

2. High Salt Content and Its Consequences

2.1. Corrosion of Steel Reinforcements

Among the most serious challenges of using beach sand in construction is salt. Seawater contains high quantities of sodium chloride (salt) that are transferred to beach sand. Using sand with high salt content in concrete causes two serious issues:

Corrosion of Reinforcement Bars (Rebars): Concrete structures typically use steel reinforcement for providing tensile strength. Salt accelerates rusting of steel, weakening the structure internally. This, in the long term, can cause buildings to weaken, requiring costly repairs or even collapse.

Reduced Concrete Strength: Salt disrupts the cement setting, resulting in weaker concrete. The chemical reaction of water and cement (hydration) is disrupted by chloride ions, preventing the strong bond from occurring.

2.2. Efflorescence and Long-Term Damage

Efflorescence consists of white deposits of salt appearing on the face of concrete and bricks as water evaporates. Efflorescence is more than a surface cosmetic issue but rather an outward sign of subsurface structural deterioration. It eventually can lead to weakening of the masonry, cracking, and compromising the overall structural integrity of buildings.

3. Environmental and Legal Restrictions

3.1. Beach Sand Mining and Ecological Damage

Even if beach sand were technically suitable for use in construction, its extraction would have disasterously adverse environmental consequences. Beaches serve as natural defenses against coastal erosion, storm surges, and sea level rise. Sand extraction disrupts these functions, leading to:

Coastal Erosion: Shorelines are left exposed to waves and tides in the absence of sand, leading to loss of land. Beaches around the world are already eroding due to human activities, and mining beach sand would worsen the situation.

Habitat Destruction: Beaches provide a home for diverse marine and terrestrial wildlife, from crabs and mollusks to nesting turtles. Removal of sand disrupts ecosystems and threatens biodiversity.

Saltwater Intrusion: Sand acts as a filter and maintains groundwater levels. Removal of sand would enable seawater to penetrate freshwater sources, making drinking water undrinkable for coastal communities.

3.2. Legal Restrictions on Sand Mining

Due to its environmental importance, most countries have strict laws against sand mining from beaches. Sand mining is a growing concern, with heavy penalties for offenders. Sand mining from authorized sources, such as riverbeds and quarries, is regulated by governments to ensure it is sustainable.

4. The Future of Sustainable Construction Materials

As worldwide sand shortages are rapidly emerging as a priority concern, researchers are exploring novel alternatives, which include:

Bioengineered Sand: Researchers are developing artificial sands by employing bacteria to collect grains into construction-grade materials.

Plastic and Industrial Waste Sand Substitutes: Researchers are working with finely shredded plastic waste and industrial byproducts (such as fly ash) as eco-friendly substitutes for natural sand.

Conclusion 

Although sand on the beach seems to be an abundant and free material for building, its rounded shape, very high salt content, and environmental degradation make it unbefitting. The structural defects it imposes, along with the environmental devastation caused by sand extraction, have led to strict bans on its utilization. River sand, manufactured sand, and new materials replace it in construction to offer strength as well as sustainability. As the demand for sand rises, it will become crucial in the future to seek out new, sustainable solutions to both build with and preserve it.